Project Description In less than 6 months, SARS-CoV-2, the virus that causes COVID-19, has spread across the globe indiscriminately infecting persons regardless of social status or age. Pregnant women and children are not spared but in contrast to other respiratory viruses, SARS-CoV-2 infection does not appear to be more severe in these groups. Nevertheless, there is considerable concern about transmission from mother to infant particularly via breast feeding. Many viral infections such as HIV, CMV, and Ebola are transmitted through breast milk. SARS-CoV-2 enters human cells using the ACE 2 receptor which is present in breast tissue. This increases concern that the virus may be present in the breast milk of infected women. Although most children do remarkably well with infection, children <1 year of age have more severe illness with high rates of hospitalization and admission to the intensive care unit. Therefore, defining the risks of SARS-CoV-2 breast milk transmission is of critical importance. However, breast milk is not only a potential vector of transmission but can be a vehicle of protection by the transfer of protective antibodies and other immune factors. Both humoral and cellular immune responses in milk, including milk antibodies to respiratory viruses such as influenza, modulate infant disease. In fact, infants less than 6 months of age rely on maternal antibodies to protect them against influenza and other respiratory viruses. Maternal flu immunization protects infants for at least 6 months not only against influenza but other febrile illnesses. Whether breast milk contains antibodies to SARS-CoV-2 and whether it modulates the risk of infection to the infant is unknown. Answering these questions will require assays to detect the virus and its immune response in milk. We propose to fill these critical gaps by validating a quantitative RT-PCR assay for detecting SARS-CoV-2 in breast milk and then testing over 100 milk samples from women infected with COVID-19. We will also test heat inactivation protocols used by breast milk banks to verify that Holder pasteurization destroys SARS-CoV-2. At present, breast milk banks will not accept donations from women who have had COVID-19. As the infection spreads this exclusion will limit the availability to sick and vulnerable infants. Finally, we will develop an assay to detect antibodies to SARS-CoV-2 expressed in breast milk and compare those to the antibodies present in maternal blood. Information about maternal transfer of SARS-CoV-2 specific antibodies to the infant is a high priority to inform both breastfeeding practices and SARS-CoV-2 vaccination strategies.